fix(graphics context setting): opacity = 1 when args.opacity is zero (falsy value) (#134)

* opacity is no longer 1 when explicitly set to 0

Author: L2jLiga

models/GraphicsContextSettings/GraphicsContextSettings.js

@@ -40,7 +40,7 @@ class GraphicsContextSettings {
     } else {
       Object.assign(this, GraphicsContextSettings.Model, args, {
         blendMode: blendModeMap[args.blendMode || 'normal'],
-        opacity: args.opacity || 1,
+        opacity: Number.isFinite(args.opacity) ? args.opacity : 1,
       });
     }
     return this;

models/GraphicsContextSettings/GraphicsContextSettings.test.js

@@ -19,4 +19,12 @@ describe('GraphicsContextSettings', () => {
     const graphicsContextSettings = new GraphicsContextSettings(null, json);
     expect(JSON.stringify(json, null, 2)).toEqual(JSON.stringify(graphicsContextSettings, null, 2));
   });
+
+  it('should correctly handle opacity = 0', () => {
+    const graphicsContextSettings = new GraphicsContextSettings({
+      opacity: 0,
+    });
+
+    expect(graphicsContextSettings.opacity).toBe(0);
+  });
 });